Science question? about step tubes

Bought some used step tubes on marketplace. I bit of rust inside the main body tubes, which was expected, but one of the steps has water in it, yet was completely sealed off. I know it was completely sealed because when I drilled out a relief hole to let the water out, I actually had a rush of air come out. Anyway, the water was black and nasty, but for weight reduction purposes, I wanted to get rid of it (better mpg ). My scientific question is how did the water get in there and how did it then seal itself off?

Should I caulk it to seal again or just let it be, so any water that does get in, can get out. Should I wool wax the whole inside to slow down the rusting process? Thanks everyone, especially the science buffs!

 

1) The water got in there because water found an intrusion point. Meaning there was a pinhole in one of the welds or in the body tubes. I bet if you went over them again very carefully you will see. Actually, if you want to find out exactly where to do this: Blow smoke into the hole that you created and you will see where it comes out. Similar to a leak down test.
2) The weight that the water added to your overall weight wasn't impacting your MPG's, but I can see why you'd want to mitigate that problem before it becomes one. Our MPG's suck balls.
3) I wouldn't seal it off. Personally I would want a drainage point. I would clean them up, hit them with a Scotch Brite pad and then hit them with 3 coats of rattle can matte-black spray paint.

P.S. WHY are they hanging so low!?!?!! Did you do that on purpose? I have the same steps (Toyota calls them Predator steps) and mine are much closer to the body of the truck.

 

+1 ^

and if there were manufactured weep/vent holes (I believe that’s what I see in your first photo) they probably corroded shut.

Those are definitely not factory Predator Tube Steps as the step framework are tubes not flat plates like the factory type.

 

I wouldnt recommend putting wax on them, thats an accident waiting to happen as your foot slides off. Im about to do my rock railes and plan on sanding any surface rust, hitting them with primer then rustoleam. Its going to keep happening, rocks hit them and chips the paint. You just have to stay on top of any new rust before the rust really starts doing damage to them.

 

Every time I see street tires on a 4Runner:

 

April Fools! That was an old pic…this better?

 

Last time I saw running boards (or whatever it's called depending) sit lower like that on here, they were meant to clear the Limited/TRD Sport's lower bodywork and it was a mixup at the dealer.

 

If you want to stop the internal rust I suggest examining the rails for a likely location to cut/drill a hole you can close up after the rust is stopped. You can tap/thread a hole for a plug. Select some type of metal, plastic or rubber plug. There are even threaded nylon plugs.
I have used a marine Rust-lock liquid for decades anytime I need to stop rust permanently. It turns rust into a grey inert material -it can be left bare or painted.

 

I think when welding a closed pipe, like our rails, a vent is required for safe welding. The intense heat will superheat the trapped air and possibly blow hot melted steel back at the welding torch and welder.

 

They’re so low cuz they’re probably after market for a different vehicle. Only 5 of the 6 bolts line up with it. Guy had a lifted 4Runner so it looked decent but mine looks like it might scrape the pavement lol. Time to lift.

Though I want to agree that the water got in there one way or another, I am absolutely
Certain this was sealed off entirely because even I drilled the hole to relieve the water, there was a rush of air when I punctured. Wouldn’t do that if there was even a tiny hole to let the water in ‍♂️

 

Oh for sure I just wanted to hit inside the main frame tubes. They’re rusty indide

 

Oh for sure I just wanted to hit inside the main frame tubes. They’re rusty inside